Isomerases, e.g., racemases, e.g., amino acid racemases, alanine racemases, and/or epimerases catalyze the re-arrangement of atoms within a molecule, catalyze the conversion of one isomer into another, catalyze the conversion of an optically active substrate into a raceme, which is optically inactive, catalyze the interconversion of substrate enantiomers, catalyze the stereochemical inversion around the asymmetric carbon atom in a substrate having only one center of asymmetry, catalyze the stereochemical inversion of the configuration around an asymmetric carbon atom in a substrate having more than one asymmetric center, and/or catalyze the racemization of amino acids. Isomerases, e.g., racemases, e.g., amino acid racemases, alanine racemases, and/or epimerases are of considerable commercial value, being used in the pharmaceutical industry, in the food, feed and beverage industries, e.g. for the production of sweeteners, in the wood/paper industry and in the fuel industry.